Anti-Ulcer Drugs Overview

Drugs to Control Acid (Ulcers)

• General MOA (Mechanism of Action): Increases dopamine function in the synaptic cleft, inhibits dopamine breakdown, and administers dopamine agonists to activate dopamine receptors.

Anti-Ulcer Drugs

• Antacids: Basic substances that neutralize stomach acid through a neutralization reaction, producing water and a salt. Absorbed into the body (systemic), or non-systemic (safer).
• Histamine-2 Receptor Antagonists: Block histamine 2 receptors on parietal cells, inhibiting stomach acid secretion. Examples include cimetidine, which inhibits some CYP450, decreasing biotransformation.
• Muscarinic Receptor Antagonists: Block muscarinic receptors on parietal cells, reducing vagus nerve influence on acid secretion. This only stops acid secretion by 40%.
• Proton-pump Inhibitors: Permanently bind to and antagonize the proton pump in the stomach, effectively blocking the final acid secretion step and protecting the stomach. Commonly end in "-prazole".
• Mucosa Protecting Agents:
  • Sucralfate: Forms a viscous gel that coats the stomach lining.
  • Misoprostol: NSAIDS inhibit the prostaglandins production in the gastric mucosa; reducing mucus and bicarbonate production.
• When to Use:
  • Antacids: Over-the-counter medications for minor gastric irritation.
  • Histamine-2 Receptor Antagonists & Proton-pump Inhibitors: More effective for suppressing acid secretion.
  • Proton-pump Inhibitors: Administered one hour before meals to maximize drug concentration when acid is secreted.
  • Mucosa Protecting Agents: Used when other methods don't work.
• Adverse Effects:
  • Antacids: Generally safe.
  • Histamine-2 Receptor Antagonists & Proton-pump Inhibitors: Potential for diarrhea and headache, especially in some people.
  • Mucosa Protecting Agents: Mostly safe, but diarrhea can be a side effect.